<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>实验</title>
    <style>
        .cl1{
            width: 50px;
            height: 50px;
            background: red;
            float: left;
        }
        .cl2{
            width: 100px;
            height: 100px;
            background: blue;
            float: left;
        }
        .cl3{
            width: 150px;
            height: 150px;
            background: yellow;
            clear: both;
        }
    </style>
</head>
<body>
    <div class="cl1">
        哈哈哈
    </div>
    <div class="cl2">
        嘿嘿嘿嘿嘿嘿
    </div>
    <div class="cl3">
        挥发发就放假啊
    </div>
</body>
</html>